Phreaky Phalangid

While searching through shortgrass prairie atop the Pine Ridge in northwestern Nebraska in hopes of finding Cicindela nebraskana (prairie long-lipped tiger beetle), this harvestman caught my eye.  Harvestmen are, of course, arachnids related to spiders, but they lack fangs and poison or silk glands and are placed the separate order Opiliones (Phalangida when I was in school).  Admittedly, I haven’t paid much attention to harvestmen before now, but this one seemed different from any I’d seen before – nearly black with relatively short legs and distinctive orange intersegmental articular membranes at the base of the legs.  Harvestmen are known to employ chemical defenses through special repugnatorial glands that produce phenols, quinones, ketones, and/or alcohols, and this individual seemed to display a clear example of aposematic coloration to warn any potential predators of its distastefulness.

Trachyrhinus favosusAlthough beetles are my focus, I normally try to do my own identifications in other groups as well.  However, some rather persistent searching through the extensive harvestman holdings at BugGuide failed to turn up a good match.  In gestalt it seemed to belong to the family Sclerosomatidae, but even that was just guessing on my part.  So, I did what I’ve done only a few times before and posted the photos to BugGuide’s ID Request.  A day and a half later I had my answer – Trachyrhinus favosus.  BugGuide Contributing Editor V. Belov had sent the photos to harvestman expert Marshal Hedin, who had this to say in response:

Cokendolpher describes males as ‘body ranging from solid black…’ with bases of femora ‘yellow-brown’. The species is also known from western Nebraska. Cool.

I was pleased to learn that these photographs represented a new species for BugGuide and no longer felt bad about not being able to find a good match.  Further, my leanings toward the family Sclerosomatidae had been confirmed.  According the Cokendolpher (1981), T. favosus ranges in a narrow band from North Dakota south to north-central Texas and is active only during fall.  I had intended to try to get an even closer photograph, but after taking the second photograph above I accidentally disturbed the critter and then watched in amazement as it began bouncing up and down vigorously.  This apparently is a defensive behavior that functions to blur the body form.  I watched it bounce and became even more amazed as it began calmly walking away while continuing its vigorous bouncing – quite a spectacle!

Photo Details: Canon 50D w/ MP-E 65mm 1-5X macro lens (ISO 100, 1/250 sec, f/13), Canon MT-24EX flash w/ Sto-Fen + GFPuffer diffusers. Typical post-processing (levels, minor cropping, unsharp mask).

REFERENCE

Cokendolpher, J. C.  1981. Revision of the genus Trachyrhinus Weed (Opiliones, Phalangioidea).  Journal of Arachnology 9:1–18.

Copyright © Ted C. MacRae 2010

About Ted C. MacRae

Ted C. MacRae is a research entomologist by vocation and beetle taxonomist by avocation. Areas of expertise in the latter include worldwide jewel beetles (Buprestidae) and North American longhorned beetles (Cerambycidae). More recent work has focused on North American tiger beetles (Cicindelidae) and their distribution, ecology, and conservation.
This entry was posted in Arachnida, Opiliones and tagged , , , , , , , . Bookmark the permalink.

14 Responses to Phreaky Phalangid

  1. Great find, Ted. Opiliones are very difficult to photograph, with her long legs and nervous character.

    • Thanks, Javier. I’ve started paying attention to other individuals since this one – you’ll see these in future posts. The super long-legged ones are extraordinarily difficult to get good, close macro shots of because they wave their extra-long 2nd pair of legs around like antennae – try to get the lens inside 10cm distance and they’re gone!

  2. I enjoy trying to photograph Opiiones, but it can be a bit difficult to get past the legs when trying to photograph the eye detail! Nice shot.

    • Thank you, Adrian. This was a pretty good one to work with for my first one, as it was a relatively short-legged species. I’ve since tried the longer-legged species and had to work much harder at it. (Of course, the greater the challenge, the more stubbornly I persist at it!)

  3. TGIQ says:

    Great shots! The descriptions of the defensive behaviour are wonderful too, I’ve never seen a harvestman do that before. Is it unique to certain species, I wonder?

  4. Dale says:

    Many years ago I saw an aggregation of harvestmen in Costa Rica all doing the hula. They were on the underside of a leaf and when I disturbed them they all began to sway in synchrony.

  5. This guy doesn’t need a costume for Halloween! Great find! I think it’s very cool this one is new to Bug Guide.

  6. Joe Fortier says:

    Really fascinating pictures, and good work Ted.
    Joe

  7. Nicholas Bell says:

    Awesome photos Ted! The composition is really good.
    Also, the first one reminds me of those huge scary machines from War of the Worlds 😀

    • Thanks, Nik. Nice analogy with ‘War of the Worlds’.

      Harvestmen are one of those things that look fairly innocuous from afar (at least here in North America) but up close have an otherworldly freakishness about them. This is even more pronounced in some of the tropical/Old World species with their spines and tubercles!

Commentaria

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s